Solve for $x$, ignoring any extraneous solutions: $\dfrac{x^2 - 4x}{x + 6} = \dfrac{-15x - 30}{x + 6}$
Solution: Multiply both sides by $x + 6$ $ \dfrac{x^2 - 4x}{x + 6} (x + 6) = \dfrac{-15x - 30}{x + 6} (x + 6)$ $ x^2 - 4x = -15x - 30$ Subtract $-15x - 30$ from both sides: $ x^2 - 4x - (-15x - 30) = -15x - 30 - (-15x - 30)$ $ x^2 - 4x + 15x + 30 = 0$ $ x^2 + 11x + 30 = 0$ Factor the expression: $ (x + 5)(x + 6) = 0$ Therefore $x = -5$ or $x = -6$ However, the original expression is undefined when $x = -6$. Therefore, the only solution is $x = -5$.